In its haste to celebrate abortion, NARAL tripped up over basic junior high level science. The pro-abortion group retweeted a tweet with the message: “I’m pro-choice because I understand that a zygote is not a baby.”

Even the Encyclopedia Britannica understands that the zygote stage is the beginning stage of human life and that conception, or fertilization, has resulted in a unique human being.

zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm). In the embryonic development of humans and other animals, the zygote stage is brief and is followed by cleavage, when the single cell becomes subdivided into smaller cells.

The zygote represents the first stage in the development of a genetically unique organism. The zygote is endowed with genes from two parents, and thus it is diploid (carrying two sets of chromosomes). The joining of haploid gametes to produce a diploid zygote is a common feature in the sexual reproduction of all organisms except bacteria.

Wikipedia also provides the basic understanding NARAL lacks about the development of a unique human person that is taking place.

A zygote (from Greek ζυγωτός zygōtos “joined” or “yoked”, from ζυγοῦν zygoun “to join” or “to yoke”),[1] is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo. In single-celled organisms, the zygote divides to produce offspring, usually through meiosis.

A zygote is always synthesized from the union of two gametes, and constitutes the first stage in a unique organism’s development. Zygotes are usually produced by a fertilization event between two haploid cells—an ovum (female gamete) and a sperm cell (male gamete)—which combine to form the single diploid cell. Such zygotes contain DNA derived from both parents, and this provides all the genetic information necessary to form a new individual.

And, as NARAL is loathe to admit, every human being alive today was once a zygote — though millions are killed annually in abortions — and people are generally zygotes before a woman first knows she is pregnant.

All mammals go through the zygote stage of life. Mammalian zygotes eventually develop into a blastocyst, after which they are more generally termed an embryo, and then a fetus. A human zygote exists for about four days, and becomes a blastocyst on the fifth day.

The simple biological truth of the matter is that the Cell Theory states that all cells arise from pre-existing cells. There is no blackout period between sperm and egg uniting, and then the emergence of ‘life’ at some point distant.

The Carnegie stages of human development indicate that human development begins in the zygotic stage. Then there is the assertion of developmental biologist and leading textbook author in the field, Scott Gilbert. In his text, Gilbert takes us through the life cycle of a dog. His text, Developmental Biology, is arguably the leading text in the field. According to Gilbert:

“Traditional ways of classifying catalog animals according to their adult structure. But, as J. T. Bonner (1965) pointed out, this is a very artificial method, because what we consider an individual is usually just a brief slice of its life cycle. When we consider a dog, for instance, we usually picture an adult. But the dog is a “dog” from the moment of fertilization of a dog egg by a dog sperm. It remains a dog even as a senescent dying hound. Therefore, the dog is actually the entire life cycle of the animal, from fertilization through death.”

First, note how he sets the word dog off in quotes at one point, to communicate the very essence of the organism:

But the dog is a “dog” from the fertilization of a dog egg by a dog sperm…

The same may be said of all vertebrates, including cats, giraffes, chimpanzees, and humans. Substituting the word human for dog in Gilbert’s analysis gets to the heart of the matter. We are human for our entire life cycle. We are whole and complete in form and function at every stage of our development, for that given developmental stage. The prepubescent child is fully human, even though they lack the capacity to execute all human functions, such as abstract reasoning, or reproduction.

In the same way, the early embryo is alive and fully human, though it has not yet executed all human organismal functions.